1. Field of the Invention
The present invention relates to a method for determining the distance of a sensor with respect to a conductive reaction rail, particularly for application with magnetic bearings or magnetic levitation devices such as are employed in magnetic transportation engineering for the positional control of support and guide magnets using a coil system at the sensor side. The coil system generates a chronologically-changing magnetic field, whereby the reactions of eddy currents induced in the reaction rail are consulted for the identification of the distance from the rail. The invention also relates to an apparatus for implementing the method.
2. Description of the Prior Art
Contact-free measurement of a distance has already been thoroughly investigated. Given such a known method, for example as set forth in the German published application 28 03 887, the distance-dependent magnetic coupling of two coils is exploited. The great sensitivity to the frequency exciting the coils, as well as to external magnetic fields, is thereby disadvantageous. In influencing of the ferro-magnetic material used to construct the sensor, due to external magnetic fields, is also thereby unfavorable because the measuring field is also influenced, as set forth in the German published application 32 37 843. As a rule, the sensors also extend over a plurality of fields of a grooved reaction rail, as disclosed in the German published application 29 16 289.